1. Field of the Invention
The present invention relates, in general, to pipe cutters and more particularly to ratchet pipe cutters for use in confined areas.
2. Description of the Prior Art
In the field of pipe cutting it is often necessary to cut pipes located in awkward and confined areas. For example, a pipe which is located in a corner with very little clearance behind the pipe presents an especially difficult cutting problem. A similar type of problem is presented when the pipe must be excavated before cutting. In such situations it is desirable to excavate only to the pipe and not far beyond as would be required to allow clearance completely around the pipe for a pipe cutter. Therefore a ratchet pipe cutter whose lever arm must travel only through a short arc is a greater advantage for cutting pipes in these confined areas.
Typical ratchet pipe cutters of the past are shown in U.S. Pat. Nos. 135,644; 784,445; 996,602, 1,117,225 and 3,252,218. Each of these pipe cutters has a pipe receiving part and a lever arm. The lever arm is used to actuate a pawl which engages ratchet teeth. This much of the ratchet pipe cutting art is common. However, a major problem with each of these prior art devices is presented in placing the pipe cutter in position on the pipe. The manner in which this problem has been treated gives insight into the difficulty of achieving a satisfactory solution.
In patents to Haynes (U.S. Pat. No. 135,644) and Braun (U.S. Pat. No. 3,252,218), the pipe-receiving part of the cutter is divided into two interlocking portions. The two portions slide into engagement to form the pipe-receiving body. This however, is a disadvantage since a relatively long section of pipe must be exposed in order to allow sliding engagement of the two parts. Another disadvantage is that the cutting members which extend from the pipe-receiving body are not amenable to sliding on a pipe. Therefore, retraction of these cutters is required during the sliding engagement of the parts. Yet another disadvantage is the requirement of machining the parts to fine tolerances for a snug fit. Without such a snug fit the parts wear quickly and the cutters do not contact the pipe properly.
In patents to Sylvester (U.S. Pat. No. 784,445), Anderson (U.S. Pat. No. 996,602) and Nash (U.S. Pat. No. 1,117,225), the pipe-receiving body is hinged. However, this hinged part must be able to cooperate with the cutters and notches. In the past this cooperation has been achieved at the expense of size. As can be seen in Sylvester, Anderson and Nash, when the lever arm is attached to the pipe-receiving body, the entire ratchet portion creates a body having a substantial circumference. This circumference is a disadvantage since the whole purpose of the ratchet pipe cutter is to allow cutting pipes with relatively small clearance available around the pipe. Of course, a larger circumference requires a larger clearance. Furthermore, the hinges of these pipe cutters interfere with the notches of the ratchet and the cutters. This interference has caused the notches to be made smaller and therefore more easily worn. It has also caused the cutters to be placed in unusual arrangements when it would be better to have them opposed to each other for offsetting the forces which must be exerted for cutting.